CRD Summary: This review assessed the frequency of cardiac valve regurgitation in patients with Parkinson's Disease treated with ergot-derived and non-ergot dopamine agonists, concluding that ergot-derived dopamine agonists (such as pergolide and cabergoline) increased their frequency. Given the variation across studies and shortcomings highlighted in the review process and reporting, the authors' conclusions should be interpreted with caution.

CRD Commentary: The review question was clear, but it was unclear whether inclusion criteria for study design and participants were adhered to. It was unclear whether randomised controlled trials were excluded from the review or that none were found. In one included study, the majority of participants had Restless Legs Syndrome, a condition that did not appear to meet the inclusion criteria for the review. The search was thorough but was restricted to publications in English. It appeared that non-English studies without an English abstract were excluded, so language bias may have been present. There was no apparent search for unpublished studies, so some studies may have been missed. The methods used for study selection and data extraction were not reported, making it unclear whether methods were used to reduce error and bias. There was no formal assessment of the validity of the included studies. Given the heterogeneity between the studies, the decision to employ a narrative synthesis was appropriate. The synthesis was poorly reported. It was unclear which studies represented better quality evidence. The review was funded by GlaxoSmithKline, the manufacturer of ropinirole (one of the drugs included in the review). In light of the between study heterogeneity, poor reporting of the review process and unclear synthesis, the authors' conclusions should be interpreted with caution.